Re: [lwip-devel] again... Zero Copy Ethernet interface

[Mike Kleshov]

> As also mentioned in the past, outgoing zero copy is more difficult because
> lwIP wants to free the pbuf after the call to low_level_input and this could
> happen before the DMA transfer has occurred.  Maybe I have this wrong but I
> recall some complication in regards to sending data.

I suppose that converting all data sending to zero-copy would take a
major revision of lwip code. But this might be easier with TCP writes.
Since TCP waits for acknowledges anyway, the pbufs with outgoing data
should live long enough. Would it be possible to inform the low-level
driver that all pfubs constituing a packet are of this kind, so the
driver can use a zero-copy routine to send it?